What does a head louse feed on on a human head? - briefly
Head lice ingest human blood by piercing the scalp with their specialized mouthparts and drawing a few drops several times daily. This protein‑rich fluid is essential for their survival and reproduction.
What does a head louse feed on on a human head? - in detail
Head lice survive exclusively by extracting human blood from the scalp. The insect inserts its slender, needle‑like mouthparts—called stylets—into a tiny puncture in the skin surrounding a hair follicle. Through this canal it draws a minute volume of blood, typically 0.5–1.0 µL per feeding episode. Feeding occurs several times a day; each bout lasts 5–10 minutes, after which the louse withdraws and returns to a secure site near the hair shaft.
Key aspects of the feeding process include:
- Target tissue: capillaries in the superficial dermis of the scalp, not the hair itself.
- Salivary components: anticoagulants and anesthetic proteins that prevent clotting and reduce host sensation.
- Frequency: adult females may feed up to 10 times daily, providing enough nutrients for egg production.
- Quantity: cumulative intake over 24 hours averages 5–10 µL, sufficient to sustain metabolism and reproduction.
- Impact on the host: repeated blood loss is negligible in volume, but saliva can provoke localized itching, erythema, and secondary bacterial infection.
The louse’s life cycle is tightly linked to this blood source. Nymphs, which hatch from eggs (nits) attached to hair shafts, begin feeding within hours and continue the same pattern until maturation. Because the parasite cannot survive without access to the scalp’s vascular supply, removal of the host’s hair or treatment that blocks the feeding apparatus effectively terminates infestation.